Rubber-reinforced thermoplastic resin composition containing particles of graft polymer

ABSTRACT

A rubber-reinforced thermoplastic resin composition is disclosed. The rubber-reinforced thermoplastic resin composition comprises a thermoplastic resin matrix having dispersed therein particles of a graft polymer, the particles of a graft polymer comprising particles of a rubber polymer having emulsion-graft-polymerized to the surface thereof two or more kinds of vinyl compounds copolymirizable with the rubber polymer, wherein the surface graft coverage of the vinyl compounds graft-polymerized to the surface of the particles of a rubber polymer as determined by equation (m1) is 80% or more and the average thickness of the vinyl compounds graft-polymerized to the surface of the particles of a rubber polymer is from 5 to 25 nm: 
     
         Surface graft coverage (%)=(s2/s1)×100               (m1) 
    
     wherein s1 represents the surface area of the particles of a rubber polymer; and s2 represents the surface area of the vinyl compound graft-polymerized to the surface of the particles of a rubber polymer so as to cover the surface of the particles of a rubber polymer.

TECHNICAL FIELD

The present invention relates to a rubber-reinforced thermoplastic resincomposition excellent in impact resistance, fluidity duringhigh-temperature processing, resistance to coloration duringhigh-temperature retention, impact resistance during high-temperatureretention, and resistance to gelation during high-temperature retention.

BACKGROUND ART

Heretofore, rubber-reinforced thermoplastic resin compositions such asan ABS resin have been widely used as general-purpose resins havingwell-balanced impact resistance, moldability, surface gloss and othermechanical properties and materials usable as a substitute ofengineering plastics.

For such a rubber-reinforced thermoplastic resin composition, impactresistance, moldability and other mechanical properties under ordinaryconditions as well as these physical properties during high-temperatureprocessing or high-temperature retention, i.e., thermal stability, arevery important. When rubber-reinforced thermoplastic resin compositionsare extrusion-granulated or molded, deterioration by heat generated byshear or heat retention can often occur, such as decrease in impactresistance of a molded product, yellowing of resin, and deterioration ofsurface gloss. Further, when heat retention proceeds, a gel-likematerial is produced in the extruder or molding machine and incorporatedin the molded product as a contaminant in the resin, causing problems.Moreover, when a large-sized product is molded or a product having acomplicated shape or small thickness is molded, the resin is oftenmolded at a high temperature so that it can be easily extended all overthe interior of the mold. In this case, problems often arise such asdecrease in impact resistance, fluidity and surface gloss.

Further, the foregoing decrease in fluidity during high-temperatureprocessing, decrease in impact resistance during high-temperatureretention, coloration during high-temperature retention, and gelationduring high-temperature retention remarkably appear when particles of arubber polymer having a large particle diameter designed to have anexcellent impact resistance under ordinary extrusion molding conditionsare used or when particles of a rubber polymer having a low gel fractioncontent are used. Therefore, it has been difficult to obtain arubber-reinforced thermoplastic resin composition excellent in impactresistance under ordinary extrusion molding conditions, fluidity duringhigh-temperature processing, impact resistance during high-temperatureretention, resistance to coloration during high-temperature retention,and resistance to gelation during high-temperature retention, when theparticles of a rubber polymer have a large particle diameter or a lowgel fraction content.

In order to solve these problems, there has been proposed to reduce theadded amount of the rubber polymer or to increase the gel fractioncontent of the rubber polymer. However, these approaches are undesirablein the design attaining high impact resistance.

Alternatively, there has been proposed to increase the percent graftamount of a vinyl compound graft-polymerized to the particles of arubber polymer shown by the following equation: ##EQU1## This approachcan maintain surface gloss at high temperatures but disadvantageouslycauses decrease in impact resistance or fluidity at ordinary moldingtemperature.

Further, there has been proposed to employ an approach which comprisesadding various oxidation inhibitors during extrusion or molding toinhibit the coloration or decrease in impact resistance due to heatdeterioration. However, this approach cannot always inhibit the decreasein impact resistance or fluidity at high temperatures or the decrease inimpact resistance during high-temperature retention. For the designattaining good impact resistance and surface gloss, U.S. Pat. No.4,009,227 employs a combination of particles of rubber having a middleto large particle diameter with particles of a rubber polymer having asmall particle diameter. However, this approach requires a complicatedpreparation process which comprises separate graft polymerization stepsof particles of rubber having a large particle diameter and theparticles of rubber having a small particle diameter, followed bymixing.

JP-A-62-164707 (The term "JP-A" as used herein means an "unexaminedpublished Japanese patent application") discloses a thermoplastic resincomposition excellent in impact resistance and surface gloss at hightemperatures containing particles of rubber having a vinyl compoundgrafted thereon to an average thickness of from 10 to 20 nm. However,the graft polymerization of a vinyl compound on particles of a rubberpolymer generally features that the greater the particle diameter of therubber polymer is, or the lower the gel fraction content of the rubberpolymer is, the more difficultly can be graft-polymerized on the surfaceof the rubber polymer the vinyl compound. Further, the present inventorshave found that in the case where the particles of a rubber polymer hasa low gel fraction content, and in the case where, even if the gelfraction content of particles of a rubber polymer is close to 100%, whenthe particles have a large particle diameter exceeding 250 nm, thethickness of the vinyl compound graft-polymerized on the surface of theparticles of a rubber polymer can be easily uneven, making it difficultto balance the impact resistance with the surface gloss at hightemperatures only by controlling the average thickness of the vinylcompound graft-polymerized on the particles of a rubber polymer.JP-A-62-164707 also does not refer to fluidity at high temperatures,coloration during high-temperature retention, impact resistance duringhigh-temperature retention, and resistance to gelation duringhigh-temperature retention.

Therefore, a rubber-reinforced thermoplastic resin composition has beenhardly provided that is excellent in impact resistance under ordinaryextrusion molding conditions, in fluidity during high-temperatureprocessing, impact resistance during high-temperature retention,resistance to coloration during high-temperature retention, onconditions that the particles of a rubber polymer have a large particlediameter and a low gel fraction content, to have an excellent impactresistance under ordinary extrusion molding conditions.

DISCLOSURE OF THE INVENTION

It is therefore an object of the present invention to provide arubber-reinforced thermoplastic resin composition excellent in impactresistance under ordinary extrusion molding conditions, as well as influidity during high-temperature processing, and impact resistance,resistance to coloration and resistance to gelation during retentioneven when the particles of a rubber polymer have a large particlediameter and a low gel fraction content.

The inventors made extensive studies on the foregoing problems. As aresult, it has been found that the surface area of the rubber polymercovered by the graft-polymerized polymer, i.e., the surface graftcoverage, and the average thickness of the layer of thegraft-polymerized polymer (graft layer) are important in the graftpolymerization of two or more kinds of vinyl compounds on the surface ofthe rubber polymer. It has been also found that when the surface graftcoverage can be raised to not less than 80%, desirable physicalproperties can be obtained even if the average thickness of the graftlayer is not more than 10 nm. It has been further found that when atleast one of emulsifying agent to be used for the emulsion graftpolymerization is an emulsifying agent having radically polymerizabledouble bonds in its molecule, it can exert an excellent effect ofsolving the foregoing problems. Thus, the present invention has beenworked out.

The present invention relates to a rubber-reinforced thermoplastic resincomposition comprising a thermoplastic resin matrix dispersed thereinparticles of a graft polymer, the particles of a graft polymercomprising particles of a rubber polymer havingemulsion-graft-polymerized to the surface thereof two or more kinds ofvinyl compounds graft-copolymerizable with the rubber polymer, whereinthe surface graft coverage of the vinyl compounds graft-polymerized tothe surface of the particles of a rubber polymer as determined byequation (m1) is 80% or more and the average thickness of the vinylcompounds graft-polymerized to the surface of the particles of a rubberpolymer is from 5 to 25 nm:

    Surface graft coverage (%)=(s2/s1)×100               (m1)

wherein s1 represents the surface area of the particles of a rubberpolymer; and s2 represents the surface area of the vinyl-compoundgraft-polymerized to the surface of the particles of a rubber polymer soas to cover the surface of the particles of a rubber polymer.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a specific example of analysis for determining thepercent surface graft coverage and the covered thickness of vinylcompound of the present invention. Numeral 1 denotes a rubber polymerand 2 denotes a vinyl compound graft-polymerized on the rubber polymer.The portions a₁ to a_(n) indicate the peripheral length of the portionon the particles of the rubber polymer that is covered by the vinylcompound. The portion b₁ to b_(n) indicate the peripheral length of theportion on the particles of the rubber polymer that is not covered bythe vinyl compound. The portions c₁ to c_(n) indicate the area of thevinyl compound.

FIG. 2 illustrates the relationship between the gel fraction content X %and the weight-average particle diameter Y nm of the present invention.

BEST MODE FOR PRACTICING INVENTION

The percent surface graft coverage as used herein is defined by thefollowing equation (m1) assuming that s1 is the surface area of theparticles of the rubber polymer (rubber polymer particles) and s2 is thesurface area of the vinyl compound grafted on the surface of the rubberpolymer particles such that it covers the surface of the rubber polymerparticles. Accordingly, the percent surface graft coverage is a measureof how extent the surface of rubber polymer particles dispersed in therubber-reinforced thermoplastic resin composition is grafted with andcovered by the graft polymer of the vinyl compound. When the rubberpolymer particles are thoroughly covered by the graft polymer, thepercent surface graft coverage is 100%.

    Surface graft coverage (%)=(s2/s1)×100               (m1)

As described later, the percent surface graft coverage can be determinedby analyzing and measuring an electron micrograph of an extremely thinsection of a graft polymer particle dispersed in the rubber-reinforcedthermoplastic resin composition. FIG. 1 schematically illustrates theelectron micrograph. Specifically, the lengths a₁ to a_(n) and b₁ tob_(n) are measured, and from these measurements, r1 and r2 representedby the following equation are then determined.

    r1=(a.sub.1 +a.sub.2 + . . . +a.sub.n-1 +a.sub.n)+(b.sub.1 +b.sub.2 + . . . +b.sub.n-1 +b.sub.n)

    r2=a.sub.1 +a.sub.2 + . . . +a.sub.n-1 +a.sub.n

Assuming that r1 is the length corresponding to the surface area of therubber polymer particles and r2 is the length corresponding to thesurface area of the vinyl compound grafted on the surface of the rubberpolymer particles such that it covers the surface of the rubber polymerparticles. The percent surface graft coverage can be determined by thefollowing equation (m1'):

    Surface graft coverage (%)=(r2/r1)×100               (m1')

In the present invention, the percent surface graft coverage is 80% ormore, preferably 90% or more. The closer to 100%, i.e., upper limit, thepercent surface graft coverage is, the more preferred is it.

If the percent surface graft coverage falls below 80%, it can oftenreduce the impact resistance of the composition. Even if there is nodecrease in the impact resistance of the composition, itdisadvantageously causes decrease in fluidity during high-temperatureprocessing, coloration by heat deterioration and production of agel-like material by retention during extrusion or molding.

Further, a rubber-reinforced thermoplastic resin composition which ismore excellent in impact resistance, fluidity during high-temperatureprocessing, impact resistance during retention, resistance to colorationduring retention and resistance to gelation during retention can beobtained when the percent surface graft coverage is not less than 80% inthe region where the weight-average particle diameter (Y nm) of therubber polymer particles contained in the thermoplastic resincomposition and its gel fraction content (X %) satisfy the conditionsrepresented by the following relationships (m2) and (m3) (regionsurrounded by the straight lines X in FIG. 2), preferably the followingequations (m4) and (m5) (region surrounded by the straight line Y inFIG. 2), more preferably the following equation (m6) (region surroundedby the straight line Z in FIG. 2).

    40≦X≦60, and 150≦Y≦600         (m2)

    60≦X≦100, and 2.5≦Y≦600        (m3)

    50≦X≦60, and 200≦Y≦500         (m4)

    60≦X≦100, and 2.5X+50≦Y≦600    (m5)

    60≦x≦80, and 2.5X+75≦Y≦450     (m6)

The average thickness of the vinyl compound grafted on the surface ofthe rubber polymer particles is preferably from 5 to 25 nm, morepreferably from 7 to 15 nm, in the region where the percent surfacegraft coverage is not less than 80%. If the average thickness of thevinyl compound grafted on the surface of the rubber polymer particlesfalls below 5 nm, it tends to cause decrease in surface gloss duringhigh-temperature processing or gelation during retention. If the averagethickness of the vinyl compound grafted on the surface of the rubberpolymer particles exceeds 25 nm, it tends to cause decrease in fluidity.

The constitution of the rubber-reinforced thermoplastic resincomposition of the present invention and the process for the preparationthereof will be described hereinafter.

Examples of the rubber polymer employable in the present inventioninclude conjugated diene rubber such as polybutadiene, polyisoprene,polychloroprene, butadiene-styrene copolymers andbutadiene-acrylonitrile copolymers; and acrylic rubber such asethylene-propylene rubber, polyethyl acrylate, and polybutyl acrylate.Preferred among these rubber polymers are conjugated diene rubber suchas polybutadiene, butadiene-styrene copolymers andbutadiene-acrylonitrile copolymers. Two or more of these rubber polymersmay be used in combination.

The content of the rubber polymer in the rubber-reinforced thermoplasticresin composition is preferably from 5 to 60% by weight, more preferablyfrom 10 to 50% by weight, based on the mount of the resin composition.In this region, better impact resistance, fluidity during molding andgloss can be provided.

A preferred particle diameter of the rubber polymer particles in therubber-reinforced thermoplastic resin composition varies depending onthe kind of the thermoplastic resin as a matrix and is not specificallylimited. When the thermoplastic resin composition is an ABS resin, theparticle diameter is preferably from 150 to 600 nm, more preferably from200 to 500 nm, particularly preferably from 250 to 450 nm. The particlediameter preferably falls within the above specified range in the lightof impact resistance and gloss.

Examples of the vinyl compound graft-polymerizable with the rubberpolymer particles employable in the present invention include (a1)aromatic vinyl compounds such as styrene and main chain- or sidechain-substituted styrene such as α-methylstyrene, (a2) vinyl cyanidecompounds such as acrylonitrile and methacrylonitrile, (a3) acrylicesters such as methyl acrylate, ethyl acrylate and butyl acrylate, andmethacrylic esters such as methyl methacrylate, (a4) acrylic acids suchas acrylic acid and methacrylic acid, (a5) maleimide monomers such asN-phenylmaleimide and N-methylmaleimide, and (a6) glycidylgroup-containing monomers such as glycidyl methacrylate. These vinylcompounds may be used in combination. Particularly preferred among theseis a combination of two or more monomers including an aromatic vinylcompound and a vinyl cyanide compound.

The relative amount of the vinyl compound graft-polymerized on therubber polymer particles, i.e., graft ratio, is represented by the ratioobtained by dividing the weight of the graft polymer particles by theweight of the original rubber polymer particles. The graft ratio ispreferably from 20% to 200% in the light of impact resistance andfluidity, more preferably from 20% to 80%.

As the thermoplastic resin used as the matrix, a polymer or copolymer ofthe foregoing monomers listed as the vinyl compounds graft-polymerizablewith the rubber polymer particles are generally used. Specific examplesof such a thermoplastic resin include acrylonitrile-styrene copolymers,acrylonitrile-styrene-α-methylstyrene copolymers,acrylonitrile-styrene-phenylmaleimide copolymers, and methylmethacrylate-styrene-acrylonitrile copolymers. Preferred among thesethermoplastic resins is a thermoplastic resin containing at least onekind of an aromatic vinyl compound and a vinyl cyanide compound.

The thermoplastic resin may be produced as a polymer or copolymer whichis not grafted in the graft polymerization process, or alternatively, itmay be polymerized in a separate process and then blended in thecomposition. The amount of the thermoplastic resin can be determined bysubtracting the total weight of the rubber polymer and the graftedpolymer or copolymer from the total weight of the rubber-reinforcedthermoplastic resin composition.

The rubber-reinforced thermoplastic resin composition of the presentinvention may be used in admixture with other thermoplastic resins thanthe above. Examples of the other thermoplastic resins includepolycarbonate, polyphenylene oxide, acrylic resin, thermoplasticpolyurethane, polyester, and polyamide. The amount of otherthermoplastic resins may be from 1 to 70% by weight based on the totalamount of the resin composition, and the amount of the rubber-reinforcedthermoplastic resin composition may be from 30 to 99% by weight based onthe total amount of the resin composition. In this amount range, ahigher impact resistance and excellent moldability at high temperatures,which are the effect of the present invention, can be enhanced.

The process for the preparation of the rubber-reinforced thermoplasticresin composition of the present invention is not specifically limited.In general, an emulsion graft polymerization process may be employedwhich comprises allowing a vinyl compound to be graft-polymerized with arubber polymer latex which has been produced by emulsion polymerization.The emulsion graft polymerization process may be effected in acontinuous process, a batch process, or a semi-batch process. Analternate process may be employed which comprises preparing a highrubber content graft polymer by the foregoing process, and then mixingtherewith a thermoplastic resin comprising, as a main component, a vinylcompound used in the graft polymerization prepared by masspolymerization, emulsion polymerization or suspension polymerization, soas to obtain a desired rubber content.

In the present invention, an emulsion graft polymerization process ispreferably employed, which comprises continuously adding, to rubberpolymer particles which has been produced by emulsion polymerization, avinyl compound together with a polymerization initiator, a molecularweight adjustor, etc. In particular, if the rubber polymer particleshave a large particle diameter and a low gel fraction content, on whicha vinyl compound can inherently be hardly grafted, it is important touse a specific emulsifying agent in the graft polymerization to raisethe surface graft coverage to not less than 80%. In other words, it isimportant to use as such an emulsifying agent, an emulsifying agentcontaining a polymerizable double bond in its molecule (hereinafterreferred to as "polymerizable emulsifying agent"). The polymerizableemulsifying agent is a compound having both a hydrophilic group and ahydrophobic group capable of lowering the gas-liquid, liquid-liquid, andsolid-liquid interfacial tension that contains one or more double bondspolymerizable with a conjugated diene rubber, an aromatic vinylcompound, a vinyl cyanide compound and/or a (meth)acrylic estercompound. The hydrophilic group contained in the polymerizableemulsifying agent may be of anionic, nonionic or cationic nature,preferably anionic nature, more preferably both nonionic nature andanionic nature.

The amount of the polymerizable emulsifying agent to be used ispreferably from 1 to 15 parts by weight per 100 parts by weight of therubber polymer particles. In this range, the graft polymerization can beconducted with a higher stability and the resulting rubber-reinforcedthermoplastic resin composition can be provided with a higher waterresistance.

In the emulsion graft polymerization, the polymerizable emulsifyingagent may be used in combination with a non-polymerizable emulsifyingagent. The amount of the non-polymerizable emulsifying agent to be usedis not more than 4.0 parts by weight based on 100 parts by weight of therubber polymer particles. The non-polymerizable emulsifying agent may bean emulsifying agent commonly used for emulsion polymerization. Specificexamples of such an emulsifying agent include anionic emulsifying agentssuch as a rhodinic acid salt, a higher aliphatic acid salt, analkylsulfuric acid ester, an alkylbenzenesulfonic acid salt, analkyldiphenyl ether disulfonate, polyoxyethylene alkyl phenyl ethersulfate, and dialkylsulfosuccinate; and nonionic emulsifying agents suchas a polyoxyethylene alkyl ether and a polyoxyethylene alkyl phenylether.

Examples of the polymerizable emulsifying agent employable in thepresent invention will be given below, but the present invention is notlimited thereto.

Polymerizable emulsifying agents represented by formula (1): ##STR1##wherein X represents an allyl group, a methylallyl group, an acryloylgroup, a methacryloyl group, a vinyl group, a 1-propenyl group, or anisopropenyl group;

Y represents a hydrogen atom, a sulfate group represented by --SO₃ M (inwhich M represents a hydrogen atom, an alkaline earth, an alkaline earthmetal, an ammonium, or a hydroxylalkylammonium having from 1 to 4 carbonatoms), a carboxylate group represented by --CH₂ COOM (in which Mrepresents a hydrogen atom, alkaline earth, alkaline earth metal,ammonium, or a hydroxylalkylammonium having from 1 to 4 carbon atoms),or a monoester phosphate group represented by formula (1'): ##STR2##wherein M₁ and M₂ may be the same or different and each represent ahydrogen atom, an alkaline metal, an alkaline earth metal, a ammonium,or a hydroxyalkylammonium having from 1 to 4 carbon atoms;

R₁ represents a alkyl group having from 1 to 18 carbon atoms, an alkenylgroup, or an aralkyl group;

R₂ represents a hydrogen atom, an alkyl group having from 1 to 18 carbonatoms, an alkenyl group, or an aralkyl group;

R₃ represents a hydrogen atom or a propenyl group;

A represents a alkylene group having from 2 to 4 carbon atoms or analkylene group having from 2 to 4 carbon atoms and having a substituent;and

m represents an integer of from 1 to 200.

The polymerizable emulsifying agents represented by formula (1) aredescribed in U.S. Pat. No. 5,332,854. Specific examples of thepolymerizable emulsifying agents represented by formula (1) includecompounds represented by formulae (5) to (8): ##STR3## wherein Mrepresents an alkaline metal, an alkaline earth metal, an ammonium, or aC₁₋₄ hydroxyalkylammonium; and n represents an integer of from 1 to 100(the expression "C₁₋₄ " and the like used herein means "having from 1 to4 carbon atoms" and the like); ##STR4## wherein M represents an alkalinemetal or an alkaline earth metal; and n represents an integer of from 1to 100; ##STR5## wherein n represents an integer of from 10 to 200; and##STR6## wherein M represents an alkaline metal, an alkaline earthmetal, an ammonium, or a C₁₋₄ hydroxyalkylammonium; and n represents aninteger of from 1 to 100.

(Meth)allylglycidylether derivatives and (meth)acrylglycidylesterderivatives represented by formula (2) (the expression "(meth)acryl" andthe like used herein means "acryl and methacryl" and the like): ##STR7##wherein X represents an allyl group, a methylallyl group, an acryloylgroup, a methacryloyl group, a vinyl group, a 1-propenyl group, or anisopropenyl group;

Y represents a hydrogen atom, a sulfate group represented by --SO₃ M (inwhich M represents a hydrogen atom, an alkaline earth, an alkaline earthmetal, an ammonium, or a hydroxylalkylammonium having from 1 to 4 carbonatoms), a carboxylate represented by --CH₂ COOM (in which M represents ahydrogen atom, an alkaline earth, an alkaline earth metal, an ammonium,or a hydroxylalkylammonium having from 1 to 4 carbon atoms), a monoesterphosphate group represented by formula (1') above, or a grouprepresented by formula (1"): ##STR8## wherein M₁ represents a hydrogenatom, an alkaline metal, an alkaline earth metal, an ammonium, ahydroxyalkylammonium having from 1 to 4 carbon atoms, or an alkyl grouphaving from 8 to 30 carbon atoms which may contain an alkylene oxidegroup having from 2 to 4 carbon atoms; and M₂ represents a hydrogenatom, an alkaline metal, an alkaline earth metal, an ammonium, or ahydroxyalkylammonium having from 1 to 4 carbon atoms;

Z represents a alkyl group having from 8 to 30 carbon atoms, asubstituted alkyl group such as hydroxyalkyl group, an alkenyl group, asubstituted alkenyl group such as a hydroxyalkenyl group, an alkylarylgroup, a substituted alkylaryl group such as a hydroxyalkylaryl group,an aralkyl aryl group, a substituted aralkyl aryl group such as ahydroxyaralkyl aryl group, an acyl group, or a substituted acyl groupsuch as a hydoxyacyl group;

A represents a alkylene group having from 2 to 4 carbon atoms or asubstituted alkylene group;

m represents an integer of from 0 to 100; and

n represents an integer of from 0 to 50.

Preferred examples of the compounds represented by formula (2) includethose represented by formulae (9) to (15): ##STR9## wherein M representsa hydrogen atom or a group --SO₃ M₁ (in which M₁ represents an alkalinemetal, an alkaline earth metal, an ammonium, or a C₁₋₄hydroxyalkylammonium); Z₁ represents a C₈₋₃₀ alkyl group or an alkylarylgroup; and m represents an integer of from 0 to 100; ##STR10## wherein Mrepresents an alkaline metal or an alkaline earth metal; Z₁ represents aC₈₋₃₀ alkyl group or an alkylaryl group; and m represents an integer offrom 0 to 100; ##STR11## wherein Y₁ represents a group represented byformula (11'): ##STR12## wherein M₁ represents a C₈₋₃₀ alkyl group whichmay contain a C₂₋₄ alkylene oxide group; and M₂ represents an alkalinemetal, an alkaline earth metal, an ammonium, or a C₁₋₄hydroxyalkylammonium; ##STR13## wherein R represents a C₄₋₃₀ alkyl groupwhich may contain substituents such as a hydroxyalkyl group; and Mrepresents an alkaline metal, an alkaline earth metal, an ammonium, or aC₁₋₄ hydroxyalkylammonium; ##STR14##

Succinic acid derivatives represented by formula (3): ##STR15## whereinX represents an allyl group, a methylallyl group, an acryloyl group, amethacryloyl group, a vinyl group, a 1-propenyl group, or an isopropenylgroup;

B₁ and B₂ are different from each other and each represent Y or Z,wherein Y represents M or --SO₃ M in which M represents a hydrogen atom,an alkaline metal, an alkaline earth metal, an ammonium, or ahydroxyalkylammonium having from 1 to 4 carbon atoms, and Z represents aalkyl group having from 8 to 30 carbon atoms or an alkenyl group;

A represents a alkylene group having from 2 to 4 carbon atoms or analkylene group having substituents; and

m and n may be the same or different and each represent an integer offrom 0 to 50.

Specific preferred examples of the compound represented by formula (3)include compounds represented by formulae (16) to (19): ##STR16##

Compounds represented by formula (4): ##STR17## wherein X represents anallyl group, a methylallyl group, an acryloyl group, a methacryloylgroup, a vinyl group, a 1-propenyl group, or an isopropenyl group;

Y represents a hydrogen atom, a sulfate group represented by --SO₃ M (inwhich M represents a hydrogen atom, an alkaline earth, an alkaline earthmetal, a ammonium or a hydroxylalkylammonium having from 1 to 4 carbonatoms), or a carboxylate group represented by --CH₂ COOM (in which Mrepresents a hydrogen atom, an alkaline earth, an alkaline earth metal,an ammonium, or a hydroxylalkylammonium having from 1 to 4 carbonatoms);

R₁ and R₃ may be the same or different and each represent a hydrogenatom, an alkyl group having from 1 to 25 carbon atoms;

R₂ and R₄ may be the same or different and each represent an alkyl grouphaving from 1 to 25 carbon atoms, a benzyl group, or a styryl group;

p represents an integer of from 0 to 2;

A represents an alkylene group having from 2 to 4 carbon atoms or analkylene group having a substituent; and

n and m may be the same or different and each represent an integer offrom 0 to 50.

Specific preferred examples of the compound represented by formula (4)include compounds represented by formulae (20) and (21): ##STR18##wherein M represents a hydrogen atom or an alkaline metal; and ##STR19##wherein M represents a hydrogen atom or an alkaline metal.

(Meth)allylether derivatives and (meth)allylester derivativesrepresented by formula (22): ##STR20## wherein X represents an allylgroup, a methylallyl group, an acryloyl group, a methacryloyl group, avinyl group, a 1-propenyl group, or an isopropenyl group;

Y represents a hydrogen atom, a methyl group, a sulfuric ester grouprepresented by --SO₃ M (in which M represents a hydrogen atom, analkaline metal, an alkaline earth metal, an ammonium, or a C₁₋₄hydroxyalkylammonium), a carboxylate group represented by --CH₂ COOM (inwhich M represents a hydrogen atom, an alkaline metal, an alkaline earthmetal, an ammonium, or a C₁₋₄ hydroxyalkylammonium), or a phosphoricmonoester represented by formula (1') above;

Z represents a C₈₋₃₀ alkyl group;

A represents a C₂₋₄ alkylene group or a substituted alkylene group;

m represents an integer of from 0 to 20; and

n represents an integer of from 0 to 50.

Specific preferred examples of the compound represented by formula (22)include compounds represented by formulae (23) and (24): ##STR21##

Diol compounds represented by formula (25): ##STR22## wherein Arepresents a C₂₋₄ alkylene group;

R₁ represents a C₈₋₂₄ hydrocarbon group;

R₂ represents a hydrogen atom or a methyl group;

m and n each may be the same or different and each represent a number offrom 0 to 100, with the proviso that the sum of m and n is from 0 to100; and

M represents a hydrogen atom, an alkaline metal, an alkaline earthmetal, an ammonium, or a C₁₋₄ hydroxyalkylammonium.

Specific preferred examples of the diol compound represented by formula(25) include compounds represented by formula (26): ##STR23## Compoundsrepresented by formula (27):

    X--Z--Y or X--Z--O(AO).sub.n --Y                           (27)

wherein

X represents an allyl group, a methylallyl group, an acryloyl group, amethacryloyl group, a vinyl group, a 1-propenyl group, an isopropenylgroup, an allyloxy group, a methallyloxy group, an acryloyloxy group, amethacryloyloxy group, or a compound represented by formula (27'):##STR24## wherein R₁ and R₂ each represent a hydrogen atom or a methylgroup;

Y represents a hydrogen atom, a sulfate group represented by --SO₃ M (inwhich M represents a hydrogen atom, an alkaline earth, an alkaline earthmetal, an ammonium, or a C₁₋₄ hydroxylalkylmmonium), an carboxylategroup represented by --CH₂ COOM (in which M represents a hydrogen atom,an alkaline earth, an alkaline earth metal, an ammonium or a C₁₋₄hydroxylalkylammonium), a monoester phosphate represented by formula(1') above, or a compound represented by formula (1") above;

Z represents a C₆₋₃₀ alkylene group;

A represents a C₂₋₄ alkylene group or a substituted alkylene group; and

m and n each may the same or different and each represent an integer offrom 0 to 50.

Specific preferred examples of the compound represented by formula (27)include compounds represented by formulae (28) to (30):

    CH.sub.2 ═CHCH.sub.2 --C.sub.12 H.sub.24 --O(CH.sub.2 CH.sub.2 O).sub.10 --CH.sub.2 COON.sub.a                           (28) ##STR25##

Preferred among these polymerizable emulsifying agents are thoserepresented by formulae (1), (2), (3), and (4). Particularly preferredamong these polymerizable emulsifying agents are those represented byformula (1).

Preferred among the polymerizable emulsifying agents represented byformula (2) are those represented by formulae (9) and (11). Specificpreferred examples of the polymerizable emulsifying agent represented byformula (9) include those represented by formulae (31) to (34). Specificpreferred examples of the polymerizable emulsifying agent represented byformula (11) include those represented by formulae (35) and (36):##STR26##

The polymerizable emulsifying agent represented by formula (1) isparticularly preferred. Specific preferred examples of the polymerizableemulsifying agent represented by formula (1) include those representedby formulae (37) to (41): ##STR27##

The percent surface graft coverage required in the present invention canbe more easily obtained by adjusting the pH value of the rubber polymerto be used in the graft polymerization to from 6.0 to 8.0. In this pHregion, the hydrolysis of the vinyl cyanide monomer can be inhibited,making it possible to reduce the burden of disposal of waste waterrelated to nitrogen compounds and enhance the conversion of polymer.

The resin composition of the present invention may optionally comprise aknown oxidation inhibitor, ultraviolet absorbent, lubricant, releasingagent, antistatic agent, fire retardant, and colorant incorporatedtherein.

EXAMPLE

The present invention will be further described in the followingexamples. However, the present invention should not be construed asbeing limited to these examples. The "parts" as used herein are byweight unless otherwise specified.

The measurement methods used in the examples of the present inventionare as follows:

Percent Surface Graft Coverage

The rubber-reinforced thermoplastic resin composition was dissolved in asolvent capable of dissolving its sol content (e.g., acetone for an ABSresin). The solution was then subjected to centrifugal separation towithdraw gel content. The gel content was then dispersed in acetone bymeans of an ultrasonic homogenizer. The dispersion was then added to thebase of an epoxy resin adhesive so that it was dispersed therein.Acetone was then removed by vacuum drying. A hardening agent for theepoxy resin adhesive was then added to and mixed with the dispersion.The mixture was then heated so that it was cured. Thus, graft polymerparticles dispersed in an epoxy resin were obtained.

The thus obtained epoxy resin containing a rubber polymer particlesdispersed therein was dyed with, for example, osmium tetraoxide for anABS resin, and then cut by an ultramicrotome to prepare an ultrathinspecimen. The specimen was observed and photographed under atransmission electron microscope. The thickness of the ultrathinspecimen was 60 nm.

In the analysis of the electron micrograph of the rubber polymerparticles, an image analyzer IP-1000 (available from Asahi Kasei KogyoK.K.) was used to measure the percent surface graft coverage.Specifically, an image in which the rubber polymer was distinguishedfrom the vinyl compound component grafted on the surface of the rubberpolymer was used. As mentioned above, in FIG. 1, the lengths a₁ to a_(n)and b₁ to b_(n) were measured, to obtain r1 and r2 represented by thefollowing equation:

    r1=(a.sub.1 +a.sub.2 + . . . +a.sub.n-1 +a.sub.n)+(b.sub.1 +b.sub.2 + . . . +b.sub.n-1 +b.sub.n)

    r2=a.sub.1 +a.sub.2 + . . . +a.sub.n-1 +a.sub.n

From r1 and r2 the percent surface graft coverage was determined by thefollowing equation (m1'):

    Surface graft coverage (%)=(r1/r2)×100               (m1')

For the measurement of the percent surface graft coverage in thefollowing examples, only rubber polymer particles having a particlediameter of not less than the particle diameter of the rubber polymermultiplied by 0.9 was selected. The number of the rubber polymerparticles thus selected for measurement was 10.

Average Thickness of Graft-polymerized Vinyl Compound

For the measurement of the thickness of the vinyl compound grafted onthe surface of the rubber polymer particles, the rubber-reinforcedthermoplastic resin composition obtained according to the presentinvention was dyed with osmium tetraoxide, and then cut by anultramicrotome to prepare an ultrathin specimen as in the measurement ofthe percent surface graft coverage. The specimen was then observed andphotographed under transmission electron microscope. For the analysis ofthe electron micrograph of the rubber polymer particles, an imageanalyzer IP-1000 (available from Asahi Kasei Kogyo K.K.) was used.Specifically, an image in which the rubber polymer was distinguishedfrom the vinyl compound component grafted on the surface of the rubberpolymer was used. In FIG. 1, the peripheral length R represented by thefollowing equation corresponding to the surface area of the rubberpolymer particles was measured. The area t represented by the followingequation corresponding to the volume of the vinyl compound grafted onthe surface of the rubber polymer particles was measured.

    R=(a.sub.1 +a.sub.2 + . . . +a.sub.n-1 +a.sub.n)+(b.sub.1 +b.sub.2 + . . . +b.sub.n-1 +b.sub.n)

    t=c.sub.1 +c.sub.2 + . . . +c.sub.n-1 +c.sub.n

From R and t, the average thickness of the vinyl compound is determinedby the following equation (m7):

    Average thickness of vinyl compound=(t/R)                  (m7)

The number of the particles measured is 10.

Weight-average Particle Diameter of Rubber Polymer Particles

A drop of a dilute solution of a rubber polymer particles was put on ametal mesh for a transmission electron microscope, and then dyed with avapor of osmium tetraoxide or ruthenium tetraoxide. The sample thus dyedwas then photographed under a transmission electron microscope. Theweight-average diameter of particles was determined by the foregoingimage analyzer IP-1000. The number of particles measured was 100.

Gel Fraction Content of Rubber Polymer

About 0.2 g of the solid content of the rubber polymer was preciselymeasured out (sample weight). If the rubber polymer was latex, methanolwas added to the latex to cause the solid content to be precipitated.The solid content thus precipitated was then dried at normaltemperatures for 24 hours to prepare a sample. The solid content wasthen dipped in 50 g of toluene solution for 24 hours for swelling. Thesample which had thus swollen was then thrown onto a 100-mesh metal netto remove the content soluble in the solvent. The insoluble contentremaining on the metal net was dried at a temperature of 130° C. for 1hour, and then precisely measured out (weight of insoluble content). Thegel fraction content was represented by the following equation (m8):##EQU2## Properties of Polybutadiene Latex

The properties of the polybutadiene latex used in the present study areset forth in Table 1.

Method for the Evaluation of Physical Properties

The methods for the evaluation of various physical properties were asfollows:

(1) IZOD impact strength

Pellets of the resin composition were molded at a molding temperature of240° C. and a mold temperature of 45° C. to obtain a test specimen. Anotched test specimen (1/2 in.×1/4 in.×5/2 in.) was prepared andsubjected to IZOD impact strength test in accordance with ASTM-D256.

(2) High temperature melt flow rate

High temperature melt flow rate was measured in accordance with JISK7210 (measuring conditions: 280° C., 5 kg load).

(3) Degree of pigmentation after retention

Pellets of the resin composition were molded at a molding temperature of240° C. and a mold temperature of 45° C. to prepare a reference testspecimen. The same pellets as used above were retained at a temperatureof 240° C. in a molding machine for 10 minutes, and then molded in thesame manner as above to obtain a test specimen. The dimension of thetest specimen: 216 mm long×12.6 mm wide×3.2 mm thick. By using SM ColorComputer (Model SM-5) (available from Suga Shikenki K.K.), the testspecimen was then measured for yellow index (ΔYI) with respect to thereference test specimen. The measuring position was the central part ofthe specimen.

(4) IZOD impact strength after retention

Pellets of the resin composition were retained at a temperature of 240°C. in a molding machine for 10 minutes, and then molded at a moldtemperature of 45° C. to obtain a test specimen. A notched test specimen(1/2 in.×1/4 in.×5/2 in.) was prepared and subjected to IZOD impactstrength test in accordance with ASTM-D256.

(5) Gelation starting time

Powder of a graft copolymer rubber (C) and a copolymer (D) describedlater which had been prepared in examples and comparative examples weremixed and kneaded at a temperature of 240° C. by means of a 30-mmextruder in such a manner that the rubber content was 30%, to preparepellets. The pellets thus obtained were then extruded at a temperatureof 280° C. and a piston falling rate of 1 mm/sec through a capillograph(available from Toyo Seiki K.K.) with an orifice diameter of 1.0 mm. Thestrand thus extruded was observed for surface condition. The gelationstarting time is defined as the time required until particles appear onthe surface of the strand.

Example 1

Into a 10-l reaction vessel were charged 40 parts (solid content) ofpolybutadiene latex (J-1) set forth in Table 1, 1 part of an emulsifyingagent represented by formula (38), and 100 parts of ion-exchanged water.The gas phase was replaced by nitrogen. The initial solution obtainedwas then heated to a temperature of 70° C. To the initial solution werethen continuously added an aqueous solution (A) having the followingcomposition and a monomer mixture (B) having the following compositionover 5 hours to conduct polymerization. After the completion ofaddition, the reaction system was kept at the same temperature for 1hour to complete the reaction.

The composition of the aqueous solution (A) was as follows:

    ______________________________________                                        Ferrous sulfate          0.005  part                                            Sodium formaldehyde sulfoxilate (SFS) 0.1 part                                Disodium ethylenediaminetetraacetate (EDTA) 0.05 part                         Ion-exchanged water 50 parts                                                ______________________________________                                    

The composition of the monomer mixture (B) was as follows:

    ______________________________________                                        Acrylonitrile           18    parts                                             Styrene 42 parts                                                              t-Dodecylmercaptan (t-DM) 0.7 part                                            Cumene hydroperoxide (CHP) 0.1 part                                         ______________________________________                                    

To the ABS latex thus obtained was then added an oxidation inhibitor.Aluminum sulfate was then added to the latex in an amount of 1.0 partper 100 parts of the polymer so that the latex was solidified. The latexwas thoroughly desalted, rinsed, and then dried to obtain graft polymerpowder (C) (the polymerization time set forth in Table 2 indicates theaddition time of the monomer B).

The graft polymer powder (C) was then mixed with a copolymer (D) havingan intrinsic viscosity of 0.47 in 30° C. methyl ethyl ketone obtained bythe solution polymerization of a monomer mixture consisting of 70% ofstyrene and 30% of acrylonitrile. The mixture was then kneaded at atemperature of 240° C. by means of a 30-mm extruder in such a mannerthat the rubber content was 20% so that it was pelletized. During thisprocess, 1.0 part of ethylene bisstearylamide (EBS) was added to themixture. The charged composition, monomer mixture, polymerization timeand extrusion conditions were as set forth in Table 2.

Examples 2 to 5

Pellets were obtained in the same manner as in Example 1 except that J-2to J-5 set forth in Table 1 were used as rubber and the chargedcomposition, monomer mixture, polymerization time and extrusionconditions were as set forth in Table 2.

Example 6

Pellets were obtained in the same manner as in Example 1 except that 33parts (solid content) of a polybutadiene latex (J-1), 7 parts of apolybutadiene latex (H-1) and 100 parts of ion-exchanged water werecharged into a 10-l reaction vessel.

Example 7

Pellets were obtained in the same manner as in Example 6 except that thepolybutadiene latex (H-1) was replaced by a polybutadiene latex (H-2).

The resulting pellets for Examples 1 to 7 were measured for theirproperties. The results obtained are shown in Table 3.

                  TABLE 1                                                         ______________________________________                                                  Kind of rubber                                                                  J-1    J-2    J-3  J-4  H-5  H-1  H-2                             ______________________________________                                        Weight average                                                                            310    220    405  305  418  140  620                               particle diameter (nm)                                                        Gel fraction (%) 71  63  62  88  87  62  75                                 ______________________________________                                    

                                      TABLE 2                                     __________________________________________________________________________                Example                                                                       1   2   3   4   5   6   7                                         __________________________________________________________________________    Graft Polymer C                                                                 Initial Solution                                                              Kind of rubber J-1 J-2 J-3 J-4 J-5 J-1/H-1 J-1/H-2                            Polybutadiene 40 40 40 40 40 33/7 33/7                                        Ion-exchanged water 100 100 100 100 100 100 100                               Emulsifying agent 1.0 1.0 1.0 1.0 1.0 1.0 1.0                                 Kind of emulsifying (38) (38) (38) (38) (38) (38) (38)                        agent                                                                         Aqueous Solution A                                                            Ferrous sulfate 0.005 0.005 0.005 0.005 0.005 0.005 0.005                     SFS 0.1 0.1 0.1 0.1 0.1 0.1 0.1                                               EDTA 0.05 0.05 0.05 0.05 0.05 0.05 0.05                                       Ion-exchanged water 50 50 50 50 50 50 50                                      Monomer Mixture B                                                             Acrylonitrile 18 18 18 18 18 18 18                                            Styrene 42 42 42 42 42 42 42                                                  t-DM 0.7 0.7 0.7 0.7 0.7 0.7 0.7                                              CHP 0.1 0.1 0.1 0.1 0.1 0.1 0.1                                               Polymerization time 5 5 5 5 5 5 5                                             Composition to be extruded                                                    Amount of C 50 50 50 50 50 50 50                                              Amount of D 50 50 50 50 50 50 50                                              Amount of EBS 1.0 1.0 1.0 1.0 1.0 1.0 1.0                                     Amount of rubber 20 20 20 20 20 20 20                                       __________________________________________________________________________

                  TABLE 3                                                         ______________________________________                                                  Example                                                                         1      2      3    4    5    6    7                               ______________________________________                                        Surface graft                                                                             100    100    100  100  100  100  100                               coverage (%)                                                                  Average graft 10.8 9.6 12.0 10.5 11.4 11.5 11.4                               thickness (nm)                                                                Izod impact strength 33 32 34 33 34 34 33                                     (kgcm/cm)                                                                     High temperature melt 111 110 105 108 103 105 107                             flow rate (g/10 min)                                                          Degree of coloring 1.9 1.9 1.8 1.8 1.8 1.9 1.9                                during retention                                                              Izod impact strength 29 32 34 33 34 34 33                                     during retention                                                              (kgcm/cm)                                                                     Gelation starting 60<  60< 60< 60< 60< 60< 60<                                time (min)                                                                  ______________________________________                                    

Examples 8 to 19

Pellets were obtained in the same manner as in Example 1 except that thecharged compositions set forth in Tables 4 and 6 were used.

Example 20

Pellets were obtained in the same manner as in Example 1 except that theemulsifying agent and polymerization time were altered as set forth inTable 6. RK in Table 6 represents potassium rhodinate (hereinafter thesame).

Example 21

Pellets were obtained by blending 60 parts by weight of therubber-reinforced thermoplastic resin composition obtained in Example 1with 40 parts by weight of a polymethyl methacrylate having a reducedviscosity of 6. The measurement of reduced viscosity was conducted in0.1% chloroform at a temperature of 25° C.

The charged composition, monomer mixture, polymerization time andextrusion conditions for Examples 8 to 21 were as set forth in Tables 4and 6.

The resulting pellets for Examples 8 to 21 were measured for theirproperties. The results obtained are shown in Tables 5 and 7.

                                      TABLE 4                                     __________________________________________________________________________                Example                                                                       8   9   10  11  12  13  14                                        __________________________________________________________________________    Graft Polymer C                                                                 Initial Solution                                                              Kind of rubber J-1 J-1 J-1 J-1 J-1 J-1 J-1                                    Polybutadiene 40 40 40 40 40 40 40                                            Ion-exchanged water 100 100 100 100 100 100 100                               Emulsifying agent 1.0 1.0 1.0 1.0 1.0 1.0 1.0                                 Kind of emulsifying (38) (38) (37) (39) (40) (41) (31)                        agent                                                                         Aqueous Solution A                                                            Ferrous sulfate 0.01 0.005 0.005 0.005 0.005 0.005 0.005                      SFS 0.2 0.1 0.1 0.1 0.1 0.1 0.1                                               EDTA 0.1 0.05 0.05 0.05 0.05 0.05 0.05                                        Ion-exchanged water 50 50 50 50 50 50 50                                      Monomer Mixture B                                                             Acrylonitrile 18 9 18 18 18 18 18                                             Styrene 42 21 42 42 42 42 42                                                  t-DM 0.7 0.5 0.7 0.7 0.7 0.7 0.7                                              CHP 0.2 0.2 0.1 0.1 0.1 0.1 0.1                                               Polymerization time 5 5 5 5 5 5 5                                             Composition to be extruded                                                    Amount of C 50 33 50 50 50 50 50                                              Amount of D 50 67 50 50 50 50 50                                              Amount of EBS 1.0 1.0 1.0 1.0 1.0 1.0 1.0                                     Amount of rubber 20 20 20 20 20 20 20                                       __________________________________________________________________________

                  TABLE 5                                                         ______________________________________                                                  Example                                                                         8      9      10   11   12   13   14                              ______________________________________                                        Surface graft                                                                             100    100    100  100  100  100  100                               coverage (%)                                                                  Average graft 14.5 7.8 9.8 10.6 12.1 10.4 9.8                                 thickness (nm)                                                                Izod impact strength 38 30 31 33 35 35 33                                     (kgcm/cm)                                                                     High temperature melt 103 85 105 110 105 106 110                              flow rate (g/10 min)                                                          Degree of coloring 1.9 2.2 1.9 1.8 1.8 1.9 1.9                                during retention                                                              Izod impact strength 31 25 28 29 30 30 32                                     during retention                                                              (kgcm/cm)                                                                     Gelation starting 60<  60< 60< 60< 60< 60< 60<                                time (min)                                                                  ______________________________________                                    

                                      TABLE 6                                     __________________________________________________________________________                Example                                                                       15  16  17  18  19  20  21                                        __________________________________________________________________________    Graft Polymer C                                                                 Initial Solution                                                              Kind of rubber J-1 J-1 J-1 J-1 J-1 J-1 J-1                                    Polybutadiene 40 40 40 40 40 40 40                                            Ion-exchanged water 100 100 100 100 100 100 100                               Emulsifying agent 1.0 1.0 1.0 1.0 1.0 1.0 1.0                                 Kind of emulsifying (33) (34) (35) (12) (16) RK (38)                          agent                                                                         Aqueous Solution A                                                            Ferrous sulfate 0.005 0.005 0.005 0.005 0.005 0.005 0.005                     SFS 0.1 0.1 0.1 0.1 0.1 0.1 0.1                                               EDTA 0.05 0.05 0.05 0.05 0.05 0.05 0.05                                       Ion-exchanged water 50 50 50 50 50 50                                         Monomer Mixture B                                                             Acrylonitrile 18 18 18 18 18 18 18                                            Styrene 42 42 42 42 42 42 42                                                  t-DM 0.7 0.7 0.7 0.7 0.7 0.7 0.7                                              CHP 0.1 0.1 0.1 0.1 0.1 0.1 0.1                                               Polymerization time 5 5 5 5 5 20 5                                            Composition to be extruded                                                    Amount of C 50 33 50 50 50 50 50                                              Amount of D 50 50 50 50 50 50 50                                              Amount of EBS 1.0 1.0 1.0 1.0 1.0 1.0 1.0                                     Amount of rubber 20 20 20 20 20 20 20                                       __________________________________________________________________________

                  TABLE 7                                                         ______________________________________                                                  Example                                                                         15     17     17   18   19   20   21                              ______________________________________                                        Surface graft                                                                             100    100    100  100  100  100  100                               coverage (%)                                                                  Average graft 12.7 10.2 11.7 11.1 11.3 11.6 10.8                              thickness (nm)                                                                Izod impact strength 34 33 35 35 34 26 19                                     (kgcm/cm)                                                                     High temperature melt 101 100 101 101 101 70 141                              flow rate (g/10 min)                                                          Degree of coloring 1.8 1.8 1.8 1.9 1.9 1.9 1.0                                during retention                                                              Izod impact strength 32 31 29 30 31 22 16                                     during retention                                                              (kgcm/cm)                                                                     Gelation starting 60<  60< 60< 60< 60< 60< 60<                                time (min)                                                                  ______________________________________                                    

Comparative Example 1

Into a 10-l reaction vessel were charged 40 parts (solid content) of thepolybutadiene latex (J-1), 1.0 part of potassium rhodinate, and 100parts of ion-exchanged water. The gas phase was replaced by nitrogen.The initial solution obtained was then heated to a temperature of 70° C.To the initial solution were then continuously added an aqueous solution(A) having the following composition and a monomer mixture (B) havingthe following composition over 5 hours. Thus, reaction was effectedunder ordinary conditions of the amount of emulsifying agent, the amountof ferrous sulfate as a catalyst, and the polymerization time. After thecompletion of addition, the reaction system was kept at the sametemperature for 1 hour to complete the reaction.

The compositions of the aqueous solution (A) and the monomer (B) werethe same as in Example 1:

The ABS latex thus obtained was then processed in the same manner as inExample 1 to obtain pellets.

Comparative Example 2

Into a 10-l reaction vessel were charged 40 parts (solid content) of thepolybutadiene latex (J-1) and 100 parts of ion-exchanged water. The gasphase was replaced by nitrogen. The initial solution obtained was thenheated to a temperature of 70° C. An aqueous solution (A) having thefollowing composition and a monomer mixture (B) having the followingcomposition were then charged into the reaction vessel at once. Thereaction mixture was allowed to undergo polymerization at a temperatureof 70° C. for 2 hours.

The composition of the aqueous solution (A) was as follows:

    ______________________________________                                        Ferrous sulfate          0.01   part                                            Sodium formaldehyde sulfoxilate (SFS) 0.3 part                                Disodium ethylenediaminetetraacetate (EDTA) 0.1 part                          Ion-exchanged water 50 parts                                                ______________________________________                                    

The composition of the monomer mixture (B) was as follows:

    ______________________________________                                        Acrylonitrile           18    parts                                             Styrene 42 parts                                                              t-Dodecylmercaptan (t-DM) 0.7 part                                            Cumene hydroperoxide (CHP) 0.3 part                                         ______________________________________                                    

The ABS latex thus obtained was then processed in the same manner as inExample 1 to obtain pellets.

Comparative Example 3

Into a 10-l reaction vessel were charged 20 parts (solid content) of thepolybutadiene latex (J-1) and 100 parts of ion-exchanged water. The gasphase was replaced by nitrogen. The initial solution obtained was thenheated to a temperature of 70° C. To the initial solution were thencontinuously added an aqueous solution (A) having the followingcomposition and a monomer mixture (B) having the following compositionover 5 hours to conduct polymerization under the conditions that therubber concentration during polymerization was low. After the completionof addition, the reaction system was kept at the same temperature for 1hour to complete the reaction.

The composition of the aqueous solution (A) was as follows:

    ______________________________________                                        Ferrous sulfate          0.01   part                                            Sodium formaldehyde sulfoxilate (SFS) 0.2 part                                Disodium ethylenediaminetetraacetate (EDTA) 0.1 part                          Ion-exchanged water 50 parts                                                ______________________________________                                    

The composition of the monomer mixture (B) was as follows:

    ______________________________________                                        Acrylonitrile           24    parts                                             Styrene 56 parts                                                              t-Dodecylmercaptan (t-DM) 1.2 parts                                           Cumene hydroperoxide (CHP) 0.4 part                                         ______________________________________                                    

To the ABS latex thus obtained was then added an oxidation inhibitor.Aluminum sulfate was then added to the latex in an amount of 1.0 partper 100 parts of the polymer so that the latex was solidified. The latexwas thoroughly desalted, rinsed, and then dried to obtain a graftpolymer powder (C).

The graft polymer powder (C) was then kneaded at a temperature of 240°C. by means of a 30-mm extruder it was pelletized. During this process,1.0 part of ethylene bisstearylamide (EBS) was added to the mixture.

Comparative Example 4

Into a 10-l reaction vessel were charged 60 parts (solid content) of thepolybutadiene latex (J-1), 1.0 part of potassium rhodinate, and 100parts of ion-exchanged water. The gas phase was replaced by nitrogen.The initial solution obtained was then heated to a temperature of 70° C.To the initial solution were then continuously added an aqueous solution(A) having the following composition and a monomer mixture (B) havingthe following composition over 3 hours to conduct polymerization underthe conditions that the rubber concentration during polymerization washigh. After the completion of addition, the reaction system was kept atthe same temperature for 1 hour to complete the reaction.

The composition of the aqueous solution (A) was the same as in Example1.

The composition of the monomer mixture (B) was as follows:

    ______________________________________                                        Acrylonitrile           12    parts                                             Styrene 28 parts                                                              t-Dodecylmercaptan (t-DM) 0.5 part                                            Cumene hydroperoxide (CHP) 0.1 part                                         ______________________________________                                    

The ABS latex thus obtained was then processed in the same manner as inExample 1 to obtain pellets.

Comparative Example 5

Pellets were obtained in the same manner as in Comparative Example 1except that a polybutadiene latex (J-4) was used instead of thepolybutadiene latex (J-1).

The charged composition, monomer mixture, polymerization time andextrusion conditions for Comparative Examples 1 to 5 were as set forthin Table 8.

The resulting pellets for Comparative Examples 1 to 5 were measured fortheir properties. The results obtained are shown in Table 9.

                  TABLE 8                                                         ______________________________________                                                   Comparative Example                                                             1       2       3     4     5                                    ______________________________________                                        Graft Polymer C                                                                 Initial Solution                                                              Kind of rubber J-1 J-1 J-1 J-1 J-4                                            Polybutadiene 40 40 20 60 40                                                  Ion-exchanged water 100 100 100 100 100                                       Emulsifying agent 1.0 1.5 1.0 1.0 1.0                                         Kind of emulsifying RK RK RK RK RK                                            agent                                                                         Aqueous Solution A                                                            Ferrous sulfate 0.005 0.01 0.01 0.005 0.005                                   SFS 0.1 0.3 0.2 0.1 0.1                                                       EDTA 0.05 0.1 0.1 0.05 0.05                                                   Ion-exchanged water 50 50 50 50 50                                            Monomer Mixture B                                                             Acrylonitrile 18 18 24 12 18                                                  Styrene 42 42 56 28 42                                                        t-DM 0.7 0.7 1.2 0.5 0.7                                                      CHP 0.1 0.3 0.4 0.1 0.1                                                       Polymerization time 5 2 5 3 5                                                 Composition                                                                   to be extruded                                                                Amount of C 50 50 50 100 33                                                   Amount of D 50 50 50 0 67                                                     Amount of EBS 1.0 1.0 1.0 1.0 1.0                                             Amount of rubber 20 20 20 20. 20                                            ______________________________________                                    

                  TABLE 9                                                         ______________________________________                                                      Comparative Example                                                             1      2       3    4     5                                   ______________________________________                                        Surface graft coverage (%)                                                                    33     41      97   81    44                                    Average graft thickness (nm) 13.3 9.6 26 4 10.7                               Izod impact strength (kgcm/cm) 8 10 19 8 19                                   High temperature 32 34 44 41 48                                               melt flow rate (g/10 min)                                                     Degree of coloring during 12.3 13.2 2.5 10.5 12.2                             retention                                                                     Izod impact strength during 6 8 12 9 13                                       retention (kgcm/cm)                                                           Gelation starting time (min) 3 4 60<  5 3                                   ______________________________________                                    

The results in Tables 3, 5, 7, and 9 show the following results.

In Example 1, the percent surface graft coverage is as high as 100%.Therefore, the resulting rubber-reinforced thermoplastic resincomposition exhibits a high impact resistance and excellent fluidity athigh temperatures, and impact resistance, resistance-to coloration andresistance to gelation during retention although the thickness of thegraft layer is as low as 9.2 nm. Similarly, the rubber-reinforcedthermoplastic resin compositions of the present invention (Examples 2 to20) fall within the specified range of the percent surface graftcoverage and the thickness of the graft layer of vinyl compound and allexhibit a high impact resistance and excellent fluidity duringhigh-temperature processing (high temperature melt flow rate), impactresistance during high-temperature retention (IZOD during retention),resistance to coloration during high-temperature retention (degree ofcoloring during retention) and resistance to gelation duringhigh-temperature retention (gelation starting time).

On the other hand, the rubber-reinforced thermoplastic resin compositionwhich deviate from the specified range of the percent surface graftcoverage of rubber polymer particles by vinyl compound exhibit a poorimpact resistance, fluidity during high-temperature processing andresistance to coloration during high-temperature retention (ComparativeExamples 1 to 3). Further, the rubber-reinforced thermoplastic resincompositions which deviate from the specified range of the thickness ofthe graft layer of vinyl compound exhibit a poor impact resistance(Comparative Example 4) or a poor resistance to gelation (ComparativeExample 5).

What is claimed is:
 1. A rubber-reinforced thermoplastic resincomposition comprising a thermoplastic resin matrix having dispersedtherein particles of a graft polymer, said particles of a graft polymercomprising particles of a rubber polymer havingemulsion-graft-polymerized to the surface thereof two or more kinds ofvinyl compounds graft-copolymerizable with said rubber polymer, whereinthe surface graft coverage of said vinyl compounds graft-polymerized tothe surface of said particles of a rubber polymer as determined byequation (m1) is 80% or more and the average thickness of said vinylcompounds graft-polymerized to the surface of said particles of a rubberpolymer is from 5 to 25 nm:

    Surface graft coverage (%)=(s2/s1)×100               (m1)

wherein s1 represents the surface area of said particles of a rubberpolymer; and s2 represents the surface area of said vinyl compoundgraft-polymerized to the surface of said particles of a rubber polymerso as to cover the surface of said particles of a rubber polymer.
 2. Arubber-reinforced thermoplastic resin composition as claimed in claim 1,wherein said particles of a rubber polymer has a gel fraction content X% and a weight-average particle diameter Y nm meeting the conditions byequations (m2) and (m3):

    40≦X≦60, and 150≦Y≦600         (m2)

    60<X≦100, and 2.5X≦Y≦600              (m3).


3. A rubber-reinforced thermoplastic resin composition as claimed inclaim 1, wherein said vinyl compound comprises an aromatic vinylcompound and a vinyl cyanide compound.
 4. A rubber-reinforcedthermoplastic resin composition as claimed in claim 1, wherein at leastone of emulsifying agents used for emulsion graft polymerization of saidvinyl compounds is an emulsifying agent having a radically polymerizabledouble bond in its molecule.
 5. A rubber-reinforced thermoplastic resincomposition as claimed in claim 4, wherein said emulsifying agent isrepresented by formula (1): ##STR28## wherein X represents an allylgroup, a methylallyl group, an acryloyl group, a methacryloyl group, avinyl group, a 1-propenyl group, or an isopropenyl group;Y represents ahydrogen atom, a sulfate group represented by --SO₃ M (in which Mrepresents a hydrogen atom, an alkaline earth, an alkaline earth metal,an ammonium, or a hydroxylalkylammonium having from 1 to 4 carbonatoms), a carboxylate group represented by --CH₂ COOM (in which Mrepresents a hydrogen atom, alkaline earth, alkaline earth metal,ammonium, or a hydroxylalkylammonium having from 1 to 4 carbon atoms),or a monoester phosphate group represented by formula (1'): ##STR29##wherein M₁ and M₂ may be the same or different and each represent ahydrogen atom, an alkaline metal, an alkaline earth metal, a ammonium,or a hydroxyalkylammonium having from 1 to 4 carbon atoms; R₁ representsa alkyl group having from 1 to 18 carbon atoms, an alkenyl group, or anaralkyl group; R₂ represents a hydrogen atom, an alkyl group having from1 to 18 carbon atoms, an alkenyl group, or an aralkyl group; R₃represents a hydrogen atom or a propenyl group; A represents a alkylenegroup having from 2 to 4 carbon atoms or an alkylene group having from 2to 4 carbon atoms and having a substituent; and m represents an integerof from 1 to
 200. 6. A rubber-reinforced thermoplastic resin compositionas claimed in claim 4, wherein said emulsifying agent is represented byformula (2): ##STR30## wherein X represents an allyl group, amethylallyl group, an acryloyl group, a methacryloyl group, a vinylgroup, a 1-propenyl group, or an isopropenyl group;Y represents ahydrogen atom, a sulfate group represented by --SO₃ M (in which Mrepresents a hydrogen atom, an alkaline earth, an alkaline earth metal,an ammonium, or a hydroxylalkylammonium having from 1 to 4 carbonatoms), a carboxylate represented by --CH₂ COOM (in which M represents ahydrogen atom, an alkaline earth, an alkaline earth metal, an ammonium,or a hydroxylalkylammonium having from 1 to 4 carbon atoms), a monoesterphosphate group represented by formula (1'), or a group represented byformula (1"): ##STR31## wherein M₁ and M₂ may be the same or differentand each represent a hydrogen atom, an alkaline metal, an alkaline earthmetal, a ammonium, or a hydroxyalkylammonium having from 1 to 4 carbonatoms, ##STR32## wherein M₁ represents a hydrogen atom, an alkalinemetal, an alkaline earth metal, an ammonium, a hydroxyalkylammoniumhaving from 1 to 4 carbon atoms, or an alkyl group having from 8 to 30carbon atoms which may contain an alkylene oxide group having from 2 to4 carbon atoms; and M₂ represents a hydrogen atom, an alkaline metal, analkaline earth metal, an ammonium, or a hydroxyalkylammonium having from1 to 4 carbon atoms; Z represents a alkyl group having from 8 to 30carbon atoms, a substituted alkyl group, an alkenyl group, a substitutedalkenyl group, an alkylaryl group, a substituted alkylaryl group, anaralkyl aryl group, a substituted aralkyl aryl group, an acyl group, ora substituted acyl group; A represents a alkylene group having from 2 to4 carbon atoms or a substituted alkylene group; m represents an integerof from 0 to 100; and n represents an integer of from 0 to
 50. 7. Arubber-reinforced thermoplastic resin composition as claimed in claim 4,wherein said emulsifying agent is represented by formula (3): ##STR33##wherein X represents an allyl group, a methylallyl group, an acryloylgroup, a methacryloyl group, a vinyl group, a 1-propenyl group, or anisopropenyl group;B₁ and B₂ are different from each other and eachrepresent Y or Z, wherein Y represents M or --SO₃ M in which Mrepresents a hydrogen atom, an alkaline metal, an alkaline earth metal,an ammonium, or a hydroxyalkylammonium having from 1 to 4 carbon atoms,and Z represents a alkyl group having from 8 to 30 carbon atoms or analkenyl group; A represents a alkylene group having from 2 to 4 carbonatoms or an alkylene group having substituents; and m and n may be thesame or different and each represent an integer of from 0 to
 50. 8. Arubber-reinforced thermoplastic resin composition as claimed in claim 4,wherein said emulsifying agent is represented by formula (4): ##STR34##wherein X represents an allyl group, a methylallyl group, an acryloylgroup, a methacryloyl group, a vinyl group, a 1-propenyl group, or anisopropenyl group;Y represents a hydrogen atom, a sulfate grouprepresented by --SO₃ M (in which M represents a hydrogen atom, analkaline earth, an alkaline earth metal, a ammonium or ahydroxylalkylammonium having from 1 to 4 carbon atoms), or a carboxylategroup represented by --CH₂ COOM (in which M represents a hydrogen atom,an alkaline earth, an alkaline earth metal, an ammonium, or ahydroxylalkylammonium having from 1 to 4 carbon atoms); R₁ and R₃ may bethe same or different and each represent a hydrogen atom, an alkyl grouphaving from 1 to 25 carbon atoms; R₂ and R₄ may be the same or differentand each represent an alkyl group having from 1 to 25 carbon atoms, abenzyl group, or a styryl group; p represents an integer of from 0 to 2;A represents an alkylene group having from 2 to 4 carbon atoms or analkylene group having a substituent; and n and m may be the same ordifferent and each represent an integer of from 0 to
 50. 9. A resincomposition comprising from 30 to 99% by weight, based on the totalamount of said resin composition, of a rubber-reinforced thermoplasticresin composition as claimed in claim 1 and from 1 to 70% by weight,based on the total amount of said resin composition, of at least onethermoplastic resin selected from the group consisting of polycarbonate,polyphenylene oxide, acryl resin, thermoplastic polyurethane, polyester,and polyamide.
 10. A process for producing a rubber-reinforcedthermoplastic resin composition as claimed in claim 1, said processcomprising graft-polymerizing particles of a rubber polymer with two ormore kinds of vinyl compounds graft-polymerizable with said rubberpolymer, under such conditions that the pH value of a graftpolymerization system of said graft polymerization is from 6.0 to 8.0.11. A rubber-reinforced thermoplastic resin composition as claimed inclaim 2, wherein at least one of emulsifying agents used for emulsiongraft polymerization of said vinyl compounds is an emulsifying agenthaving a radically polymerizable double bond in its molecule.
 12. Aresin composition comprising from 30 to 99% by weight, based on thetotal amount of said resin composition, of a rubber-reinforcedthermoplastic resin composition as claimed in claim 2 and from 1 to 70%by weight, based on the total amount of said resin composition, of atleast one thermoplastic resin selected from the group consisting ofpolycarbonate, polyphenylene oxide, acryl resin, thermoplasticpolyurethane, polyester, and polyamide.